Apparatus and method for etching metal nitrides

ABSTRACT

Devices and methods for selectively etching a metal nitride layer are disclosed. The methods comprise an oxidation step and an etching step which are optionally separated by a purge, and which can be repeated in a cyclical etching process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/084,904 filed Sep. 29, 2020 titled APPARATUS AND METHOD FOR ETCHING METAL NITRIDES, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

The present disclosure generally relates to an apparatus for processing semiconductor wafers. More particularly, the disclosure relates to an apparatus and methods for etching metal nitrides.

BACKGROUND OF THE DISCLOSURE

Metal nitrides can be used during semiconductor device manufacture. Such layers may be patterned e.g., by a sequence of photolithographic and etching steps. In prior art methods, however, it may be difficult to control the amount of material which is removed in an etching step.

In view of the above, there is a need for improved methods and devices for etching metal nitrides.

SUMMARY OF THE DISCLOSURE

In accordance with at least one embodiment of the invention, a method for etching a metal nitride layer disposed on a substrate is disclosed, the method comprising providing a substrate in a reaction chamber of a semiconductor processing device, the substrate comprising a metal nitride layer; the method further comprising executing one or more etching cycles, an etching cycle comprising the following steps, in the following order: an oxidation step that comprises providing a gaseous oxidizing agent to the reaction chamber, thereby oxidizing a surface layer of the metal nitride layer, thus forming a metal oxide surface layer overlying an unaffected metal nitride layer; an etching step that comprises providing a gaseous etchant to the reaction chamber, thereby selectively etching the metal oxide surface layer with respect to the unaffected metal nitride layer.

In some embodiments, the metal nitride layer comprises a transition metal nitride.

In some embodiments, the metal nitride layer comprises a metal nitride selected from the list consisting of hafnium nitride, titanium nitride, vanadium nitride, tantalum nitride, zirconium nitride, yttrium nitride, niobium nitride, copper nitride, molybdenum nitride, and tungsten nitride.

In some embodiments, the metal nitride layer comprises vanadium nitride.

In some embodiments, the metal nitride layer comprises molybdenum nitride.

In some embodiments, the gaseous oxidizing agent is selected from the list consisting of O₂, O₃, H₂O, and H₂O₂.

In some embodiments, the oxidation step comprises generating an O₂ plasma in the reaction chamber.

In some embodiments, the gaseous etchant comprises a halogen.

In some embodiments, the gaseous etchant comprises chlorine.

In some embodiments, the gaseous etchant is selected from HCl, CCl₄, BCl₃, and Cl₂.

In some embodiments, the gaseous etchant comprises fluorine.

In some embodiments, the gaseous etchant is selected from the list consisting of CF₄, C₂F₈, and SF₆.

In some embodiments, the etching step comprises providing a chlorine-containing plasma in the reaction chamber.

In some embodiments, the oxidation step and the etching step are separated by a post-oxidation purge step.

In some embodiments, the method comprises two or more etching cycles, wherein subsequent etching cycles are separated by a post-etch purge step.

In some embodiments, the post-oxidation purge step and/or the post-etch purge step comprise providing a purge gas to the reaction chamber.

In some embodiments, the purge gas comprises N₂ or a noble gas.

In some embodiments, the purge gas comprises at least one of Ar and He.

In some embodiments, the purge gas comprises N₂.

In some embodiments, the post-oxidation purge step and/or the post-etch purge step comprise evacuating the reaction chamber.

Further described is metal nitride etching system for etching a metal nitride film disposed on a substrate, the system comprising: a reaction chamber configured to hold and process a substrate, the substrate comprising a metal nitride layer; a gaseous oxidizing agent source comprising a gaseous oxidizing agent selected from the list consisting of O₂, O₃, H₂O, and H₂O₂, the gaseous oxidizing agent source being configured to provide the gaseous oxidizing agent to the reaction chamber in an oxidizing agent pulse; and, a gaseous etchant source comprising a gaseous etchant, the gaseous etchant source being configured to provide the gaseous etchant to the reaction chamber in an etchant pulse.

In some embodiments, the metal nitride etching system further comprises a controller configured for causing the system to execute a plurality of etching cycles, the etching cycles each comprising an oxidizing agent pulse and an etchant pulse.

In some embodiments, the metal nitride etching system further comprises a plasma source, the plasma source being configured for exciting the gaseous oxidizing agent and/or the gaseous etchant, thus forming an excited gaseous oxidizing agent and/or an excited gaseous etchant.

In some embodiments, the plasma source is a remote plasma unit positioned upstream of the reaction chamber, and the excited gaseous oxidizing agent comprises oxygen radicals.

In some embodiments, the plasma source is a direct plasma unit positioned in the reaction chamber, and the excited gaseous oxidizing agent comprises oxygen ions.

In some embodiments, the plasma source is configured for mixing the gaseous oxidizing agent and/or the gaseous etchant with a noble gas before exciting the gaseous oxidizing agent and/or the gaseous etchant.

In some embodiments, the gaseous etchant comprises a halogen.

In some embodiments, the metal nitride etching system as described herein comprises a controller configured for causing the system to execute a method as described herein.

Further described herein is a metal nitride etching system for etching a metal nitride film disposed on a substrate, the system comprising: a reaction chamber comprising a substrate support configured to hold and process a substrate, the substrate comprising a metal nitride layer; a gaseous oxidizing agent connector fluidly connected to an oxidizing agent gas line arranged for providing a gaseous oxidizing agent to the reaction chamber, the gaseous oxidizing agent being selected from the list consisting of O₂, O₃, H₂O, and H₂O₂; a gaseous etchant connector fluidly connected to a etchant gas line arranged for providing a gaseous etchant to the reaction chamber, the gaseous etchant being selected from HCl and Cl₂; an exhaust for removing unused gaseous oxidizing agent, unused gaseous etchant, and metal nitride-derived reaction products from the reaction chamber.

In some embodiments, the metal nitride etching system further comprises a controller comprising a memory and a processor, the controller being configured for causing the metal nitride etching system to execute a plurality of etching cycles comprising an oxidizing agent pulse and an etchant pulse.

In some embodiments, the metal nitride etching system comprises a showerhead injector in fluid connection with the oxidizing agent gas line and the etchant gas line, and the metal nitride etching system is arranged for providing the gaseous oxidizing agent and the gaseous etchant to the reaction chamber.

In some embodiments, the metal nitride etching system further comprises a purge gas connector and a purge gas line, the purge gas connector being arranged for receiving a purge gas, the purge gas connector being in fluid connection with the purge gas line, the purge gas line linking the purge gas connector with the reaction chamber.

In some embodiments, the purge gas is a noble gas.

In some embodiments, the controller is configured for causing the system to separate subsequent oxidizing agent pulses and etchant pulses by a purge step.

In some embodiments, the controller is configured for causing the system to separate subsequent etching cycles by a purge step.

In some embodiments, the metal nitride etching system as described herein further comprises an RF source electrically connected to the showerhead injector. The substrate support is grounded by means of a ground, and the controller is configured for providing a plasma between the substrate support and the showerhead injector.

In some embodiments, the controller is configured to ignite the plasma during the oxidizing agent pulses and/or during the etchant pulses.

In some embodiments, the controller is configured to ignite the plasma continuously.

Further described herein is a metal nitride etching system for etching a metal nitride film disposed on a substrate, the system comprising: a reaction chamber comprising a substrate support configured to hold and process a substrate, the substrate comprising a metal nitride layer; a remote plasma source; a gaseous oxidizing agent connector fluidly connected to an oxidizing agent gas line arranged for providing a gaseous oxidizing agent to the remote plasma source, the gaseous oxidizing agent being selected from the list consisting of O₂, O₃, H₂O, and H₂O₂; a gaseous etchant connector fluidly connected to a gaseous etchant gas line arranged for providing a gaseous etchant to the remote plasma source, the gaseous etchant being selected from HCl and Cl₂; an exhaust for removing unused gaseous oxidizing agent, unused gaseous etchant, and metal nitride-derived reaction products from the reaction chamber.

In some embodiments, the metal nitride etching system is configured for executing a method as described herein.

Further described herein is a platform tool comprising a metal nitride etching system as described herein, a substrate moving device, and a metal nitride deposition system. The substrate moving device is configured for moving a substrate in the platform tool. Also, the metal nitride deposition system comprises a reaction chamber comprising a substrate support for supporting the substrate, a metal precursor source containing a metal precursor, a co-reactant connector arranged for receiving a co-reactant, a metal precursor gas line linking the metal precursor source with the reaction chamber, and a co-reactant gas line linking the co-reactant connector with the reaction chamber; the co-reactant gas line linking the co-reactant connector with the reaction chamber. The metal nitride deposition system further comprises an exhaust arranged for removing unused metal precursor, unused co-reactant, and reaction products from the reaction chamber.

In some embodiments, the metal nitride deposition system further comprises a controller comprising a memory and a processor. The controller is configured for causing the metal nitride deposition system to execute a plurality of deposition cycles. The deposition cycles comprise a metal precursor pulse in which a metal precursor is introduced in the reaction chamber, and a co-reactant pulse in which a co-reactant is introduced in the reaction chamber.

In some embodiments, the metal precursor is a vanadium precursor.

In some embodiments, the vanadium precursor is selected from the list consisting of vanadium halides, vanadium beta diketonates, vanadium oxyalkoxides, and vanadyl beta diketonates.

In some embodiments, the co-reactant comprises a nitrogen-containing gas selected from the list consisting of NH₃, N₂H₂, and N₂.

In some embodiments, the co-reactant further comprises H₂.

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the invention disclosed herein are described below with reference to the drawings of certain embodiments, which are intended to illustrate and not to limit the invention.

FIG. 1 shows a metal nitride etching system (100) according to an embodiment of the present disclosure.

FIG. 2 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 3 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 4 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 5 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 6 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 7 shows another embodiment of a metal nitride etching system (100) as described herein.

FIG. 8 shows an embodiment of a platform tool (1000) as described herein.

FIG. 9 shows an exemplary vanadium nitride deposition system (200) for use in platform tool (1000), together with a metal nitride etching system (100) as described herein.

FIG. 10 shows an exemplary embodiment of a method (1100) as disclosed herein.

Throughout the figures, the following numbering is adhered to: 100—metal nitride etching system; 110—reaction chamber; 111—showerhead injector; 120—substrate support; 130—gaseous oxidizing agent source; 131—gaseous oxidizing agent connector; 135—gaseous etchant source; 136—gaseous etchant connector; 150—oxidizing agent gas line; 155—etchant gas line; 170—RF source; 175—ground; 180—remote plasma source; 181—excited oxidizing agent line; 186—excited etchant line; 190—controller; 200—vanadium nitride deposition system; 210—reaction chamber; 220—substrate support; 230—vanadium precursor source; 236—co-reactant connector; 250—vanadium precursor gas line; 255—co-reactant gas line; 260—exhaust; 290—controller; 300—substrate moving device; 1000—platform tool.

It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

Described herein is a method for etching a metal nitride layer. The metal layer can be disposed on a substrate such as a semiconductor wafer, e.g., a monocrystalline silicon wafer, e.g., a czochralski or floatzone monocrystalline silicon wafer. The method comprises providing a substrate in a reaction chamber of a semiconductor processing device. The substrate comprises a metal nitride layer. The method then comprises subjecting the substrate to one or more etching cycles. An etching cycle comprises, in the following order, an oxidation step and an etching step. The oxidation step comprises providing a gaseous oxidizing agent to the reaction chamber. The oxidation step results in an oxidation of the surface layer of the metal nitride layer. Thus, a metal oxide surface layer is formed overlying a part of the metal nitride layer which is substantially unaffected by the oxidation step. After the oxidation step, a gaseous etchant is introduced into the reaction chamber. Thus, the metal oxide surface layer is selectively etched with respect to the substantially unaffected metal nitride layer. In other words, the etchant used has a substantially higher etch rate with respect to the metal oxide surface layer compared to the substantially unaffected metal nitride layer, e.g., an etch rate which is 2.0, 4.0, 8.0, 16.0, or 30.0 times higher.

In some embodiments, the metal nitride layer comprises a transition metal. In other words, in some embodiments, the metal nitride layer comprises a transition metal nitride.

In some embodiments, the metal nitride layer comprises a metal nitride selected from the list consisting of hafnium nitride, titanium nitride, vanadium nitride, tantalum nitride, zirconium nitride, yttrium nitride, niobium nitride, copper nitride, molybdenum nitride, and tungsten nitride.

In some embodiments, the metal nitride is selected from the list of titanium nitride, vanadium nitride, molybdenum nitride, tungsten nitride, niobium nitride, and tantalum nitride.

In some embodiments, the metal nitride layer substantially consists of vanadium nitride.

In some embodiments, the metal nitride layer substantially consists of titanium nitride.

In some embodiments, the metal nitride comprises hafnium nitride, and the metal precursor comprises a hafnium precursor. The hafnium precursor may, in some embodiments, be selected from the list consisting of hafnium halides, hafnium beta diketonates, and hafnium oxyalkoxides.

In some embodiments, the metal nitride comprises titanium nitride, and the metal precursor comprises a titanium precursor. The titanium precursor may, in some embodiments, be selected from the list consisting of titanium halides, titanium beta diketonates, and titanium oxyalkoxides.

In some embodiments, the metal nitride comprises vanadium nitride, and the metal precursor comprises a vanadium precursor. The vanadium precursor may, in some embodiments, be selected from the list consisting of vanadium halides, vanadium beta diketonates, vanadium oxyalkoxides, and vanadyl beta diketonates.

In some embodiments, the metal nitride comprises tantalum nitride, and the metal precursor comprises a tantalum precursor. The tantalum precursor may, in some embodiments, be selected from the list consisting of tantalum halides, tantalum beta diketonates, and tantalum oxyalkoxides.

In some embodiments, the metal nitride comprises zirconium nitride, and the metal precursor comprises a zirconium precursor. The zirconium precursor may, in some embodiments, be selected from the list consisting of zirconium halides, zirconium beta diketonates, and zirconium oxyalkoxides.

In some embodiments, the metal nitride comprises yttrium nitride, and the metal precursor comprises an yttrium precursor. The yttrium precursor may, in some embodiments, be selected from the list consisting of yttrium halides, yttrium beta diketonates, and yttrium oxyalkoxides.

In some embodiments, the metal nitride comprises niobium nitride, and the metal precursor comprises a niobium precursor. The niobium precursor may, in some embodiments, be selected from the list consisting of niobium halides, niobium beta diketonates, and niobium oxyalkoxides.

In some embodiments, the metal nitride comprises copper nitride, and the metal precursor comprises a copper precursor. The copper precursor may, in some embodiments, be selected from the list consisting of copper halides, copper beta diketonates, and copper oxyalkoxides.

In some embodiments, the metal nitride comprises molybdenum nitride, and the metal precursor comprises a molybdenum precursor. The molybdenum precursor may, in some embodiments, be selected from the list consisting of molybdenum halides, molybdenum beta diketonates, and molybdenum oxyalkoxides.

In some embodiments, the metal nitride comprises tungsten nitride, and the metal precursor comprises a tungsten precursor. The tungsten precursor may, in some embodiments, be selected from the list consisting of tungsten halides, tungsten beta diketonates, and tungsten oxyalkoxides.

In some embodiments, the gaseous oxidizing agent is selected from the list consisting of O₂, O₃, H₂O, and H₂O₂.

In some embodiments, the oxidation step comprises generating a plasma, e.g., an O₂ plasma in the reaction chamber. The plasma can be a direct plasma. Alternatively, the plasma can be a remote plasma. A remote plasma can be generated in the reaction chamber, e.g., separated from the substrate by a mesh plate, or it can be generated outside the reaction chamber, in which case a reactive species conduit can be provided between the remote plasma source and the reaction chamber to deliver reactive species to the reaction chamber.

In some embodiments, the O₂ plasma is provided at a plasma power of at least 50 W to at most 500 W, or at a plasma power of at least 50 W to at most 100 W, or at a plasma power of at least 100 W to at most 250 W, or at a plasma power of at least 250 W to at most 500 W.

When an O₂ plasma is generated in the reaction chamber, the oxidizing agent can, in some embodiments, comprise an oxidizing gas mixture comprising O₂ mixed with a noble gas such as He or Ar. For example, the O₂ concentration in the oxidizing gas mixture can be from at least 10 vol. % to at most 50 vol. %, or from at least 10 vol. % to at most 20 vol. %, or from at least 20 vol. % to at most 30 vol. %, or from at least 30 vol. % to at most 40 vol. %, or from at least 40 vol. % to at most 50 vol. %. Such oxidizing gas mixtures can advantageously improve plasma ignition.

In some embodiments, the gaseous etchant comprises a halogen.

In some embodiments, the gaseous etchant comprises chlorine. In some embodiments, the gaseous etchant is selected from HCl, CCl₄, BCl₃, and Cl₂.

In some embodiments, the gaseous etchant comprises fluorine. In some embodiments, the gaseous etchant is selected from the list consisting of CF₄, C₂F₈, and SF₆.

In some embodiments, providing a gaseous etchant to the reaction chamber comprises providing a plasma to the reaction chamber, such as a halogen-containing plasma. In other words, in some embodiments, the gaseous etchant comprises a halogen-containing plasma. In some embodiments, the plasma is a remote plasma. Alternatively, the plasma may be a direct plasma.

It shall be understood that “direct plasma” refers to a plasma which is maintained in the reaction chamber. In other words, when a direct plasma is used, the substrate can be positioned in the plasma, or the substrate can be positioned adjacent to the plasma. In other words, when a direct plasma is used, the substrate is directly exposed to the plasma.

It shall be understood that “remote plasma” refers to a plasma which is maintained at a certain distance from the substrate. A “remote plasma” can be maintained in plasma unit which is separate and distinct from the reaction chamber.

In some embodiments, providing a gaseous etchant to the reaction chamber comprises providing a chlorine-containing plasma in the reaction chamber. In other words, in some embodiments, the gaseous etchant comprises a chlorine-containing plasma. In some embodiments, the plasma is a remote plasma. Alternatively, the plasma may be a direct plasma.

In some embodiments, the steps of providing a gaseous oxidizing agent to the reaction chamber and providing a gaseous etchant to the reaction chamber are separated by a post-oxidation purge step.

In some embodiments, the presently described methods comprise two or more etching cycles, and subsequent etching cycles are separated by a post-etch purge step.

The post-oxidation purge step and/or the post-etch purge step may comprise providing a purge gas to the reaction chamber. By supplying a purge gas, the total pressure may be kept approximately constant in the reaction chamber during a purge step.

In some embodiments, the post-oxidation purge step and/or the post-etch purge step may comprise evacuating the reaction chamber. In other words, the post-oxidation purge step and/or the post-etch purge step may comprise removing gasses from the reaction chamber by means of a gas removing device such as a pump, while no additional gasses are provided to the reaction chamber. Accordingly, the total pressure in the reaction chamber can drop during such purge steps and/or post-etch purge steps.

In some embodiments, the post-oxidation purge step comprises evacuating the reaction chamber, and the post-etch purge step comprises providing a purge gas to the reaction chamber. In some embodiments, the post-oxidation purge step comprises providing a purge gas to the reaction chamber, and the post-etch purge step comprises evacuating the reaction chamber.

In some embodiments, the purge gas comprises a noble gas. Suitable noble gasses include Ar and He. Additionally or alternatively, the purge gas can comprise a nitrogen-containing gas such as N₂.

In some embodiments, the post-oxidation purge and/or the post-etch purge has a duration from at least 5 s to at most 60 s, or from at least 5 s to at most 10 s, or from at least 10 s to at most 20 s, or from at least 20 s to at most 40 s, or from at least 40 s to at most 60 s.

In some embodiments, and during the post-oxidation purge and/or during the post-etch purge, the purge gas is provided to the reaction chamber at a flow rate of at least 0.5 slm to at most 5 slm, or of at least 0.5 slm to at most 1 slm, or of at least 1 slm to at most 2.5 slm, or of at least 2.5 slm to at most 5 slm.

In some embodiments, the reaction chamber is, at least while executing the method, maintained at a pressure of at least 10 mTorr to at most 10 Torr, or at a pressure of at least 10 mTorr to at most 25 mTorr, or at a pressure of at least 25 mTorr to at most 50 mTorr, or at a pressure of at least 50 mTorr to at most 100 mTorr, or at a pressure of at least 100 mTorr to at most 250 mTorr, or at a pressure of at least 250 mTorr to at most 500 mTorr, or at a pressure of at least 500 mTorr to at most 1 Torr, or at a pressure of at least 1 Torr to at most 2.5 Torr, or at a pressure of at least 2.5 Torr to at most 5 Torr, or at a pressure of at least 5 Torr to at most 10 Torr.

In some embodiments, the reactor chamber is maintained, at least while executing the method, at a temperature of less than 450° C., or at a temperature of at least 50° C. to at most 450° C., or at a temperature of at least 50° C. to at most 100° C., or at a temperature of at least 100° C. to at most 150° C., or at a temperature of at least 150° C. to at most 200° C., or at a temperature of at least 200° C. to at most 250° C., or at a temperature of at least 250° C. to at most 300° C., or at a temperature of at least 300° C. to at most 350° C., or at a temperature of at least 350° C. to at most 400° C., or at a temperature of at least 400° C. to at most 450° C.

In some embodiments, the oxidizing step has a duration from at least 30 seconds (s) to at most 10 minutes (min), or from at least 1 s to at most 10 s, or from at least 10 s to at most 30 s, or from at least 30 s to at most 1 min, or from at least 1 min to at most 2.5 min, or from at least 2.5 min to at most 5 min, or from at least 5 min to at most 10 min, or from at least 10 min to at most 20 min.

In some embodiments, the etching step has a duration from at least 30 seconds (s) to at most 10 minutes (min), or from at least 1 s to at most 10 s, or from at least 10 s to at most 30 s, or from at least 30 s to at most 1 min, or from at least 1 min to at most 2.5 min, or from at least 2.5 min to at most 5 min, or from at least 5 min to at most 10 min, or from at least 10 min to at most 20 min.

In some embodiments, the oxidizing step and the etching step have an identical duration. In some embodiments, the oxidizing step and the etching step have a different duration.

In some embodiments, the flow rate at which the oxidizing agent is provided to the reaction chamber is from at least 0.1 standard liters per minute (slm) to at most 10 slm, or of at least 0.1 slm to at most 0.25 slm, or of at least 0.25 slm to at most 0.5 slm, or of at least 0.5 slm to at most 1.0 slm, or of at least 1.0 slm to at most 2.5 slm, or of at least 2.5 slm to at most 5.0 slm, or of at least 5.0 slm to at most 10.0 slm.

The oxidizing and/or etching steps may be performed in a reaction chamber for performing epitaxial deposition, chemical vapor deposition (CVD), atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), or plasma enhanced chemical vapor deposition (PECVD). The etching and/or oxidizing steps may also take place in a vertical furnace.

Thus, further described herein is a system for etching a film disposed on a substrate. The system comprises a reaction chamber configured to hold and process a substrate. The substrate comprises a metal nitride layer. The system further comprises a gaseous oxidizing agent source which in turn comprises a gaseous oxidizing agent selected from the list consisting of O₂, O₃, H₂O, and H₂O₂. The gaseous oxidizing agent source is configured to provide the gaseous oxidizing agent to the reaction chamber. The gaseous oxidizing agent can be provided to the reaction chamber in one or more gaseous oxidizing agent pulses. The system further comprises a gaseous etchant source. The gaseous etchant source comprises a gaseous etchant, and the gaseous etchant source is configured to provide the gaseous etchant to the reaction chamber. The gaseous etchant can be provided to the reaction chamber in one or more gaseous etchant pulses. Suitable gaseous etchants include halogens and halogen-containing compounds. The etchant may comprise, for example, Cl₂ or a chlorine-containing gas such as HCl.

In some embodiments, the system further comprises a controller configured for causing the system to execute a plurality of etching cycles. An etching cycle comprises an oxidizing agent pulse and an etchant pulse.

In some embodiments, the system further comprises a plasma source. The plasma source being configured for exciting the gaseous oxidizing agent and/or the gaseous etchant, thus forming an excited gaseous oxidizing agent and/or an excited gaseous etchant.

In some embodiments, the plasma source comprises a direct plasma source positioned in the reaction chamber, and the excited gaseous oxidizing agent comprises oxygen ions.

In some embodiments, the plasma source is configured for mixing the gaseous oxidizing agent and/or the gaseous etchant with a noble gas before exciting the gaseous oxidizing agent and/or the gaseous etchant.

Mixing the gaseous oxidizing agent may be done, for example, by providing the gaseous oxidizing agent and the noble gas to the remote plasma source by means of separate gas pipes. Alternatively, mixing the gaseous oxidizing agent may be done, for example, by mixing the gaseous oxidizing agent and the noble gas before they are provided to the remote plasma source, and by providing the gaseous oxidizing agent and the noble gas to the remote plasma source by means of a single gas pipe.

Mixing the gaseous etchant may be done, for example, by providing the gaseous etchant and the noble gas to the remote plasma source by means of separate gas pipes. Alternatively, mixing the gaseous etchant may be done, for example, by mixing the gaseous oxidizing agent and the noble gas before they are provided to the remote plasma source, and by providing the gaseous oxidizing agent and the noble gas to the remote plasma source by means of a single gas pipe.

In some embodiments, the plasma source is a remote plasma unit positioned upstream of the reaction chamber, and the excited gaseous oxidizing agent comprises oxygen radicals.

In accordance with at least one embodiment of the invention, a metal nitride etching system (100) is disclosed in FIG. 1. The metal nitride etching system (100) comprises: a reaction chamber (110) comprising a substrate support (120) for supporting a substrate, a gaseous oxidizing agent source (130), a gaseous etchant source (135), an oxidizing agent gas line (150) linking the gaseous oxidizing agent source (130) with the reaction chamber (110), and an etchant gas line (155) linking the gaseous etchant source (135) with the reaction chamber (110). The system (100) further comprises an exhaust (160) for removing unused gaseous oxidizing agent, unused gaseous etchant, and reaction products from the reaction chamber (110). Suitable oxidizing agent sources (130) include gas bottles containing gaseous oxidizing agent. Suitable gaseous etchant sources (135) include gas bottles containing gaseous etchant. The metal nitride etching system (100) can further comprise a controller (190) comprising a memory and a processor, and configured for causing the metal nitride etching system (100) execute a plurality of etching cycles. An etching cycle comprises an oxidizing agent pulse and an etchant pulse.

In some embodiments, the reaction chamber (110) comprises a showerhead injector (111), or simply “showerhead”, for providing the gaseous oxidizing agent and the gaseous etchant to the reaction chamber (110). Suitably, the oxidizing agent gas line (150) and the etchant gas line (155) provide oxidizing agent and gaseous etchant to the reaction chamber (110) via the showerhead injector (111). In some embodiments, the showerhead injector comprises oxidizing agent orifices for providing oxidizing agent to the reaction chamber, and separate gaseous etchant orifices for providing gaseous etchant to the reaction chamber (both not shown). The provision of separate orifices, i.e., openings, for the oxidizing agent and the gaseous etchant can be useful for avoiding or at least minimizing unwanted side reactions between oxidizing agent and gaseous etchant.

FIG. 2 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 2 is identical to that of FIG. 1, except that it does not comprise a gaseous oxidizing agent source (130) or a gaseous etchant source (135). Instead, the system of FIG. 2 comprises a gaseous oxidizing agent connector (131) and a gaseous etchant connector (136). Suitable gaseous etchant connectors and gaseous oxidizing agent connectors as such are known in the Art.

The gaseous oxidizing agent connector (131) is in fluid connection with the oxidizing agent gas line (150) linking the gaseous oxidizing agent connector (131) with the reaction chamber (110), and can be suitably connected to an out-of-system oxidizing agent gas line that provides an oxidizing agent.

The gaseous etchant connector (136) is in fluid connection with the etchant gas line (155) linking the gaseous etchant source (135) with the reaction chamber (110), and can be suitably connected to an out-of-system etchant gas line that provides a gaseous etchant. The out-of-system etchant gas line can provide etchant from, for example, an etchant gas bottle located in a cleanroom support area, in a gas bunker, or located in an outside gas storage shed.

FIG. 3 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 3 is identical to that of FIG. 2, except in that it further comprises an RF source (170) electrically connected to the showerhead injector (111), and in that the substrate support (120) is grounded by means of a ground (175). Thus, a direct plasma can be created between the substrate support (120) and the showerhead injector (111). In the embodiment of FIG. 3, the controller can be further configured to ignite the plasma during the oxidizing agent pulses and/or during the etchant pulses. In some embodiments, the controller can be configured to ignite the plasma continuously.

FIG. 4 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 4 is identical to that of FIG. 2, except in that it further comprises a remote plasma source (180), and in that the gaseous oxidizing agent connector (131) brings oxidizing agent to the remote plasma source (180) instead of to the reaction chamber (110). During normal operation, the remote plasma source (180) excites the oxidizing agent to produce excited species such as radicals, which are then brought to the reaction chamber via an excited oxidizing agent line (181).

FIG. 5 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 5 is identical to that of FIG. 2, except in that it further comprises a remote plasma source (180), and in that the gaseous etchant connector (136) brings etchant to the remote plasma source (180) instead of to the reaction chamber (110). During normal operation, the remote plasma source (180) excites the etchant to produce excited species such as radicals, which are then brought to the reaction chamber via an excited etchant line (186).

FIG. 6 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 6 is identical to that of FIG. 2, except in that it further comprises a remote plasma source (180), in that the gaseous oxidizing agent connector (131) brings gaseous oxidizing agent to the remote plasma source (180) instead of to the reaction chamber (110), and in that the gaseous etchant connector (136) brings etchant to the remote plasma source (180) instead of to the reaction chamber (110). The controller (190) is configured, e.g., by means of programming or through a hardware implementation, for causing the remote plasma source (180) to alternatingly i) excite the oxidizing agent to produce excited species such as radicals which are then brought to the reaction chamber via an excited oxidizing agent line, and ii) excite the etchant to produce excited species such as radicals which are then brought to the reaction chamber via an excited etchant line (186). Alternatively, a single gas line, i.e., an excited species line (not shown), can be used to bring the excited etchant and the excited oxidizing agent to the reaction chamber (110).

FIG. 7 shows another embodiment of a metal nitride etching system (100) as described herein. The system of FIG. 7 is identical to that of FIG. 2, except in that it further comprises a purge gas connector (139) and a purge gas line (159). The purge gas connector (139) is in fluid connection with the purge gas line (159) linking the purge gas connector (139) with the reaction chamber (110), and can be suitably connected to an out-of-system purge gas line that provides a purge gas. Suitable purge gasses include noble gasses such as He and Ar. The controller (190) is configured, e.g., by means of programming or through a hardware implementation, for causing the system to separate subsequent oxidizing agent pulses and etchant pulses by a purge and/or for causing the system to separate subsequent etchant pulses and oxidizing agent pulses by a purge. Additionally or alternatively, the controller (190) can be configured for causing the system to separate subsequent etching cycles by a purge.

In some embodiments, the purge gas configuration of FIG. 7 can be used in a remote plasma system, e.g., as shown in FIG. 3. In some embodiments, the purge gas configuration of FIG. 7 can be used in a direct plasma system, e.g., as shown in any one of FIGS. 4 to 6. In such embodiments, the controller can be configured to ignite the plasma during the purges. Alternatively, the controller can be configured to extinguish the plasma during the purges. In some embodiments, the controller is configured to ignite the plasma during the oxidizing agent pulses and during the etchant pulses, and to extinguish the plasma during the purges. In some embodiments, the controller is configured to ignite the plasma during the oxidizing agent pulses, during the etchant pulses, and during the purges; that is, the controller is configured for keeping the plasma always on.

FIG. 8 shows an embodiment of a platform tool (1000) as described herein. The platform tool (1000) comprises a metal nitride etching system (100) as described herein, e.g., according to any one of FIGS. 1 to 7. The platform tool (1000) further comprises a vanadium nitride deposition system (200) and a substrate moving device (300). The substrate moving device is configured from moving substrates in the platform tool (1000). The platform tool further comprises a controller (1090) comprising a memory and a processor, and configured (e.g., programmed or hard-wired) to cause the substrate moving device (300) to move a substrate from the vanadium nitride deposition system (200) to the metal nitride etching system (100). An exemplary vanadium nitride deposition system (200) is described with reference to FIG. 9.

FIG. 9 shows an exemplary vanadium nitride deposition system (200) for use in a platform tool (1000), together with a metal nitride etching system (100) as described herein, e.g., a metal nitride etching system (100) according to any one of FIGS. 1 to 7. The vanadium nitride deposition system (200) a reaction chamber (210) comprising a substrate support (220) for supporting a substrate, a vanadium precursor source (230), a co-reactant connector (236), a vanadium precursor gas line (250) linking the vanadium precursor source (230) with the reaction chamber (210), and a co-reactant gas line (255) linking the co-reactant connector (236) with the reaction chamber (210). The co-reactant gas line (255) links the co-reactant connector (236) with the reaction chamber (210), and can be suitably connected to an out-of-system co-reactant gas line that provides a co-reactant. The system (200) further comprises an exhaust (260) for removing unused vanadium precursor, unused co-reactant, and reaction products from the reaction chamber (210). Suitable vanadium precursor sources (230) include gas bottles containing vanadium precursor. As an alternative to the co-reactant connector (236), a co-reactant source may be used. Suitable co-reactant sources include gas bottles containing gaseous etchant. The vanadium nitride deposition system (200) can further comprise a controller (290) comprising a memory and a processor, and configured for causing the vanadium nitride deposition system (200) to execute a plurality of deposition cycles. A deposition cycle comprises a vanadium precursor pulse and a co-reactant pulse. Thus, the vanadium nitride deposition system (200) can operate in a cyclic deposition mode, e.g., in an atomic layer deposition (ALD) mode. Alternatively, the controller can be configured for continuously providing the vanadium precursor and the co-reactant to the reaction chamber. Thus, the vanadium nitride deposition system (200) may operate in a chemical vapor deposition (CVD) mode. In some embodiments, the vanadium nitride deposition system (200) is arranged for a plasma-enhanced deposition process, e.g., arranged for direct plasma or for remote plasma. The vanadium nitride deposition system (200) can be used, for example, for selectively depositing a vanadium nitride layer.

It shall be understood that suitable vanadium precursors include vanadium halides such as vanadium(III) chloride. Other suitable vanadium precursors include vanadium beta diketonates such as Vanadium(III) acetylacetonate. Other suitable vanadium precursors include Vanadium(V) oxyalkoxides such as Vanadium(V) oxytriethoxide, Vanadium(V) oxytriisopropoxide, and Vanadium(V) oxytripropoxide. Other suitable vanadium precursors include vanadyl beta diketonates such as Vanadyl acetylacetonate.

It shall be understood that suitable co-reactants include nitrogen-containing gasses such as NH₃, N₂H₂, N₂, and mixtures thereof. Other suitable co-reactants include mixtures of H₂ and a nitrogen-containing gas, e.g., a nitrogen-containing gas selected from the list consisting of NH₃, N₂H₂, N₂, and mixtures thereof.

FIG. 10 shows an exemplary embodiment of a method as disclosed herein. The method comprises a step of providing a substrate to an etching chamber (1110). The substrate comprises a metal nitride layer, for example a vanadium nitride layer. Then, the method comprises a step of providing a gaseous oxidizing agent to the reaction chamber (1120). Optionally, the reaction chamber is then purged by means of an oxidizing agent purge (1125). Then, the method comprises a step of providing a gaseous etchant to the reaction chamber (1130). Optionally, the reaction chamber is then purged by means of an etchant purge (1140). In some embodiments, the step of providing a gaseous oxidizing agent to the reaction chamber (1120), the optional oxidizing agent purge (1125), the step of providing a gaseous etchant to the reaction chamber (1130), and the optional etchant purge (1140) are repeated thus resulting in a cyclical process comprising a plurality of etching and deposition steps which are optionally separated by purges.

The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

The particular implementations shown and described are merely illustrative of the invention and are not intended to otherwise limit the scope of the aspects and implementations in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationship or physical connections may be present in the practical system, and/or may be absent in some embodiments.

It is to be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various acts illustrated may be performed in the sequence illustrated, in other sequences, or omitted in some cases.

The subject matter of the present disclosure includes all novel and nonobvious combinations and sub-combinations of the various processes, systems, and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof. 

1. A method for etching a metal nitride layer disposed on a substrate, the method comprising providing a substrate in a reaction chamber of a semiconductor processing device, the substrate comprising a metal nitride layer; the method further comprising executing one or more etching cycles, an etching cycle comprising the following steps, in the following order: an oxidation step that comprises providing a gaseous oxidizing agent to the reaction chamber, thereby oxidizing a surface layer of the metal nitride layer, thus forming a metal oxide surface layer overlying an unaffected metal nitride layer; an etching step that comprises providing a gaseous etchant to the reaction chamber, thereby selectively etching the metal oxide surface layer with respect to the unaffected metal nitride layer.
 2. The method according to claim 1 wherein the metal nitride layer comprises a transition metal nitride.
 3. The method according to claim 1 wherein the metal nitride layer comprises at least one of vanadium nitride and molybdenum nitride.
 4. The method according to claim 1 wherein the gaseous oxidizing agent is selected from the list consisting of O₂, O₃, H₂O, and H₂O₂.
 5. The method according to claim 1 wherein the oxidation step comprises generating an O₂ plasma in the reaction chamber.
 6. The method according to claim 1 wherein the gaseous etchant comprises a halogen.
 7. The method according to claim 1 wherein the gaseous etchant comprises chlorine.
 8. The method according to claim 1 wherein the gaseous etchant comprises fluorine.
 9. The method according to claim 1 wherein the etching step comprises providing a chlorine-containing plasma in the reaction chamber.
 10. The method according to claim 1 wherein the oxidation step and the etching step are separated by a post-oxidation purge step.
 11. The method according to claim 1 comprising two or more etching cycles, wherein subsequent etching cycles are separated by a post-etch purge step.
 12. The method according to claim 10 wherein at least one of the post-oxidation purge step and a post-etch purge step comprise providing a purge gas to the reaction chamber.
 13. The method according to claim 12 wherein the purge gas comprises N₂ or a noble gas.
 14. The method according to claim 10 wherein at least one of the post-oxidation purge step and a post-etch purge step comprise evacuating the reaction chamber.
 15. A metal nitride etching system for etching a metal nitride film disposed on a substrate, the system comprising: a reaction chamber configured to hold and process a substrate, the substrate comprising a metal nitride layer; a gaseous oxidizing agent source comprising a gaseous oxidizing agent selected from the list consisting of O₂, O₃, H₂O, and H₂O₂, the gaseous oxidizing agent source being configured to provide the gaseous oxidizing agent to the reaction chamber in an oxidizing agent pulse; a gaseous etchant source comprising a gaseous etchant, the gaseous etchant source being configured to provide the gaseous etchant to the reaction chamber in an etchant pulse.
 16. The metal nitride etching system according to claim 15 further comprising a controller configured for causing the system to execute a plurality of etching cycles, the etching cycles each comprising an oxidizing agent pulse and an etchant pulse.
 17. The metal nitride etching system according to claim 15 further comprising a plasma source, the plasma source being configured for exciting the gaseous oxidizing agent and/or the gaseous etchant, thus forming an excited gaseous oxidizing agent and/or an excited gaseous etchant.
 18. The metal nitride etching system according to claim 17 wherein the plasma source comprises a remote plasma unit positioned upstream of the reaction chamber, and wherein the excited gaseous oxidizing agent comprises oxygen radicals.
 19. The metal nitride etching system according to claim 17 wherein the plasma source comprises a direct plasma unit positioned in the reaction chamber, and wherein the excited gaseous oxidizing agent comprises oxygen ions.
 20. A platform tool comprising a metal nitride etching system according to claim 15, a substrate moving device, and a metal nitride deposition system, wherein the substrate moving device is configured for moving a substrate in the platform tool; the metal nitride deposition system further comprising a reaction chamber comprising a substrate support for supporting the substrate, a metal precursor source containing a metal precursor, a co-reactant connector arranged for receiving a co-reactant, a metal precursor gas line linking the metal precursor source with the reaction chamber, and a co-reactant gas line linking the co-reactant connector with the reaction chamber; the co-reactant gas line linking the co-reactant connector with the reaction chamber; and, the metal nitride deposition system further comprising an exhaust arranged for removing unused metal precursor, unused co-reactant, and reaction products from the reaction chamber. 